﻿using System;
using System.Collections.Generic;
using System.Text;

namespace ProblemsSet
{
    public class Problem_25 : BaseProblem
    {
        public override object GetResult()
        {
            return GetFubonacci(1000).Count;
        }

        public static List<string> GetFubonacci(int maxLength)
        {
            var res = new List<string> {"1", "1"};
            while (res[res.Count-1].Length < maxLength)
            {
                res.Add(MathLogic.SummString(res[res.Count-2], res[res.Count-1]));
            }
            return res;
        }

        public override string Problem
        {
            get
            {
                return @"The Fibonacci sequence is defined by the recurrence relation:

Fn = Fn1 + Fn2, where F1 = 1 and F2 = 1.
Hence the first 12 terms will be:

F1 = 1
F2 = 1
F3 = 2
F4 = 3
F5 = 5
F6 = 8
F7 = 13
F8 = 21
F9 = 34
F10 = 55
F11 = 89
F12 = 144
The 12th term, F12, is the first term to contain three digits.

What is the first term in the Fibonacci sequence to contain 1000 digits?";
            }
        }

        public override bool IsSolved
        {
            get
            {
                return true;
            }
        }

        public override object Answer
        {
            get
            {
                return 4782;
            }
        }

    }
}
